SUBSCRIBER'S CALL IDENTIFYING DISCRIMINATOR Russian patent published in 1999 - IPC

FIELD: automatic control and communications including electronic fire alarm. SUBSTANCE: device has a number of subscriber's sensors each being provided with interface unit connected to power supply through first resistor and single shared alarm line; it also has series-interconnected pulse generator, pulse selector, counter, register, and decoder with light-indicator unit, as well as voice indicator unit, pulse shapers, NAND coincidence circuits, OR circuits, flip-flops, and push-button whose first contact is connected to common wire. One channel of device functions to compare length of signal arriving at shared alarm line with maximum possible length of expected noise. Second channel is used to determine difference between length of signal arriving at shared alarm line and predetermined maximum possible length of expected noise; if this difference is above zero, data on mentioned difference is stored in register. Third channel is control channel that functions to generate signal enabling transmission of information about address of subscriber's sensor that has operated to audio and light indicating units or signal disabling transmission of such information. It also initiates device resetting. EFFECT: improved reliability of subscriber call and eliminated noise appearing during address pulse transmission. 2 cl, 3 dwg